Development and Testing of an Aberration-Correction System for Photoelectron Microscopes and Other High Resolution Imaging Systems.

用于光电子显微镜和其他高分辨率成像系统的像差校正系统的开发和测试。

• 批准号: 9418884
• 负责人: O. Griffith
• 金额: $ 37.94万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-04-15 至 1998-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9418884&HistoricalAwards=false
• 关键词: Development; Testing; Aberration; Correction; System

The goal of this project is to achieve in electron optics what was done in light optics over two hundred years ago: that is, to develop the electron optical equivalent of the acromat. When completed, this will be the first practical device to simultaneously correct both spherical and chromatic aberrations in electron optics. The two key elements are an electron mirror and a beam separating system. The mirror has aberrations of opposite sign from those of conventional electron lenses and thus provides a means of canceling out aberrations. This grant renewal seeks funds to carry out the third phase of this project. The first phase covered the design and construction of an electron mirror, beam separator, and the electron lenses, and theoretical and experimental investigations of the mirror properties (G. F. Rempfer J Appl. Phys. 67, 6027-6040 (1990)). The second phase (just completed) produced the first successful demonstration of the correction of chromatic aberration by means of an electron mirror (G. F. Rempfer and M. S. Mauck, Optik (1992) 86, 3-8), and the completion of an advanced electron optical bench to carry out high precision testing of an aberration corrector. The goal of the proposed third phase is to utilize this unique resource, (the new electron optical bench, the only one in existence designed for branched systems), to demonstrate correction of spherical aberration, and simultaneous correction of chromatic and spherical aberration. When the conditions for correction have been established, resolution tests will be performed. Tests will be done first in the probe mode. The correction parameters will then be adjusted for cancellation of aberrations in the photoelectron microscope (PEM), and resolution tests will be performed in the PEM mode. The bench studies will lead to optimum positioning of the components of the optical system and locations of the feedthroughs, manipulators, and ports, so that a less bulky vacuum housing can be designed which wi ll serve the purpose of providing a workable prototype instrument. The new housing will free up the optical bench for continuing experiments with other branched systems. A promising byproduct of this research is the beam separator, which can serve to separate the incident and returning beams in a low energy electron microscope/mirror electron microscope (LEEM/MEM). In fact, the first LEEM and MEM images of biological specimens (cultured mammalian cells) were recently obtained with the beam separating system developed as part of this project (O H. Griffith et al., J Micros. 168, 249-258 (1991)). Because the branched system is common to both LEEM/MEM and corrected PEM, the new vacuum housing for the corrected-PEM can be designed to enable LEEM and MEM studies as well. The research planned for this proposed five-year NSF grant renewal will result in an aberration-corrected lens system (i.e. an electron optical acromat) and a modular instrument intended primarily for corrected PEM, but capable also of LEEM and MEM. The higher resolution PEM should produce sharp imagines of DNA and DNA-protein complexes having information (photoelectron contrast) not available in the present imaging methods. Other applications include receptor distributions on the surfaces of normal and malignant cells, and imaging membranes and cytoskeletal elements. A hallmark of this research collaboration between a physics and engineering team (at Portland State University in Portland) and a molecular biology group (at the University of Oregon, Eugene) is the rapid application in the biological sciences of the instrumental advances funded by this NSF grant.

这个项目的目标是在电子光学方面实现200多年前在光光学方面所做的事情：即开发电子光学等价物丙烯酸钾。建成后，这将是第一个同时校正电子光学中的球差和色差的实用设备。两个关键部件是电子镜和分束系统。这种反射镜具有与传统电子透镜相反的象差，因此提供了一种消除象差的方法。这次赠款续期寻求资金，以实施该项目的第三阶段。第一阶段包括电子反射镜、分束器和电子透镜的设计和构造，以及反射镜性能的理论和实验研究(G.F.Rempfer J Appl.太棒了。67、6027-6040(1990))。第二阶段(刚刚完成)第一次成功地演示了利用电子镜(G.F.Rempfer和M.S.Mauck，Optik(1992)86，3-8)纠正色差，并建成了一台先进的电子光学实验台，以便对象差校正器进行高精度测试。拟议的第三阶段的目标是利用这一独特的资源(新的电子光学工作台，现有的唯一为分支系统设计的)来演示球差的校正，以及色差和球差的同时校正。当校正条件建立后，将进行分辨率测试。测试将首先在探测模式下进行。然后将调整校正参数以消除光电子显微镜(PEM)中的像差，并将在PEM模式下执行分辨率测试。试验台研究将导致光学系统组件的最佳位置以及馈线、机械手和端口的位置，从而可以设计出体积更小的真空外壳，从而提供可行的原型仪器。新的外壳将腾出光学工作台，以便继续进行其他分支系统的实验。这项研究的一个很有前途的副产品是光束分离器，它可以用来分离低能电子显微镜/镜面电子显微镜(LEEM/MEM)中的入射和返回光束。事实上，生物标本(培养的哺乳动物细胞)的第一个LEEM和MEM图像是最近通过作为该项目的一部分开发的光束分离系统获得的(O H.Griffith等人，J Micros。168、249-258(1991年))。由于分支系统是LEEM/MEM和修正后的PEM所共有的，因此修正后的PEM的新真空室可以设计成能够同时进行LEEM和MEM研究。为这项拟议的五年NSF拨款续期计划的研究将导致一个像差校正透镜系统(即电子光学Acroat)和一个主要用于校正PEM的模块化仪器，但也能够用于LEEM和MEM。更高分辨率的PEM应该能产生清晰的DNA和DNA-蛋白质复合体的图像，这些图像具有目前成像方法所不具备的信息(光电子对比度)。其他应用包括正常和恶性细胞表面的受体分布，以及成像膜和细胞骨架元件。波特兰州立大学的物理和工程团队和俄勒冈大学尤金分校的分子生物学小组之间的这项研究合作的一个特点是，由NSF拨款资助的仪器进步在生物科学中的快速应用。